The effects of cell adhesion on the growth and protein productivity of animal cells

摘要

We investigated the effect of cell adhesion on cellgrowth and productivity of recombinant protein inChinese hamster ovary (CHO) cells. Cells cultured innormal tissue culture dishes attached to the dishsurfaces and grew as a monolayer, while cells culturedin non-treated dishes proliferated in suspension assingle cells without adhering to the dish surfaces. On an agarose-coated dish surface, cell aggregatesformed without attaching to the dish. Growth rates inboth suspension cultures were slightly lower thanthose in monolayer culture. Cell cycle analysisindicated that the duration of the G1 phase insuspension cultures was longer than that in monolayerculture, suggesting that attachment to the substratummainly affected the transition from the G1 to theS phase. Consistent with this, CDK inhibitor p27,that inhibits the G1S transition, was induced inthe cells cultured in suspension.To assess the productivity of recombinant proteins,CHO cells were transfected with a plasmid containingmurine interferon γ (mIFN-γ) under thecontrol of the cytomegalovirus promoter. Insuspension culture, mIFN-γ productivity wasslightly lower than that in the monolayer culture. When protein kinase C was activated by phorbol ester,mIFN-γ production was enhanced in both themonolayer and suspension cultures. However, theproductivity in the suspension culture was lower thanthat in the adherent culture even in the presence ofhigh concentrations of phorbol ester. These resultssuggested that cell adhesion to the substratum affectsvarious features of CHO cells.